1. Field of the Invention
This invention relates to electric discharge lamps and has particular reference to an improved fluorescent lamp of compact size and high brightness that is suitable for use as a replacement for incandescent lamps of the type employed in residential and commercial lighting fixtures.
2. Description of the Prior Art
Electric discharge lamps having envelopes which are internally partitioned to provide one or more elongated discharge paths are well known in the art. U.S. Pat. No. 2,121,333 issued June 21, 1938 to Barclay discloses such a lamp having glass panels which are joined to the glass envelope and serve as the partition means. U.S. Pat. No. 3,024,383 issued March 6, 1962 to Doering discloses the use of a thin sheet of glass or ceramic, or a stiffened sheet of fiberglass or the like, as the partition component for a fluorescent lamp. The partition is supported by a disc-like base member that is seated on top of the stem and short-circuiting of the arc is prevented by thickening the edges and/or elastically seating the edges of a glass-textile or fiberglass partition against the envelope wall, or by providing the edges of a rigid partition with a compressible or elastic border or lining of fiberglass.
Fluorescent lamps having partitions that are fabricated from sheet metal which is coated with phosphor are also known in the art and are disclosed in U.S. Pat. No. Re. 22,896, issued July 8, 1947 to Polevitzky and U.S. Pat. No. 3,508,103 issued Apr. 21, 1970 to Young, the author of the present invention. A single-ended fluorescent lamp which contains a concentric glass cylinder and several electrodes which are sequentially energized in such a manner that the arc passes through the cylindrical partition and sweeps around the annular chamber defined by the partition and the envelope is disclosed in U.S. Pat. No. 3,609,436 issued Sept. 28, 1971 to Campbell.
Low-pressure double-ended discharge lamps that contain a filler component comprising a grooved glass rod, a series of mica discs or glass wool that is positioned between the electrodes and causes the discharge to follow different paths in random fashion and thus produce a changing or animated luminous effect are described in U.S. Pat. No. 2,133,205 issued Oct. 11, 1938 to McCauley. A fluorescent lamp that contains a plug of glass wool or metal foil which fills the chambers behind the electrodes at each end of the envelope and prevents the lamp from triggering an explosion in mines or similar environments, should the glass envelope be broken, is disclosed in U.S. Pat. No. 2,824,993 issued Feb. 25, 1958 to DiVriend et al.